This invention relates to a scroll fluid machine with a silencer that reduces as much as possible noise caused by the discharge of a compressed gas during operation.
A scroll fluid machine itself is known among those skilled in the art. In order to more easily understand the present invention, an example of the basic construction will be explained with reference to FIG. 6.
FIG. 6 is a vertical cross-sectional view of a known scroll fluid machine in which, by having an orbiting scroll with a fixed amount of eccentricity move in an orbiting motion inside a housing, a gas is sucked in from the outside of the housing and directed to a compression section that is formed by a combination of an orbiting scroll and stationary scrolls, and after becoming compressed by moving toward the center, the gas is discharged from the center.
The housing 21 which has a disk-shaped sealed compression chamber 22 comprises a casing 23 and cover 24, and has an inlet hole 25 formed in its outer circumferential surface.
Both the casing 23 and cover 24 have stationary end plates 26, 27 that are located on both sides of the compression chamber 22 so that they face each other, and spiral stationary wraps 28, 29 are formed on the inner surfaces of these end plates that face toward the side of the compression chamber 22, and form stationary scrolls 30, 31.
An orbiting scroll 32 is located inside the compression chamber 22 between both of the stationary end plates 26, 27 so that it moves in an orbiting motion around the axis of the compression chamber 22.
The orbiting scroll 32 has orbiting wraps 34, 35 that are formed on both surfaces of an orbiting end plate 33, fit inside and engage with the stationary scrolls 30, 31 and are 180° with respect thereof. The orbiting scroll 32 is supported by bearings 40, 41 so that it can turn around the eccentric shaft portion 39 of a drive shaft 38, which is fitted inside the center of the housing 21 by bearings 36, 37.
The orbiting end plate 33 is linked to the stationary end plates 26, 27 by way of three known pin-crank-type self-rotation-prevention mechanisms (not shown) that are evenly spaced from each other and located around the same circumference. When the drive shaft 38 rotates, the orbiting end plate 33 moves in an eccentric orbiting motion inside the compression chamber 22 so that the dimension in the radial direction of the space between the stationary wraps 28, 29 and orbiting wraps 34, 35, which are engaged with each other, changes.
An outlet hole 43 is formed in the stationary end plate 27 at a location near the center of the casing 23. The inner end of the outlet hole 43 opens at a location near the center of the pressure chamber 22, and the outer end is closed off by a stopper 42.
Also, a discharge hole 44 is formed radially of the stationary end plate 27 so that it extends from the outlet hole 43 to the outer surface, and a exhaust joint 45 with a check valve fits into the outer end radially of this discharge hole 44.
The drive shaft 38 is driven by a motor (not shown), and cooling fans 46, 47 are installed on the drive shaft 38 outside the casing 23 and the cover 24.
A plurality of radial cooling fins 48, 49 protrude from the rear surface of the casing 23 and cover 24.
As the drive shaft 38 rotates, the orbiting scroll 32, which is supported so that it turns around the eccentric-shaft portion 39, moves in an orbiting motion while still being engaged with the stationary scrolls 30, 31 with a constant amount of eccentricity. As it moves, a gas is sucked in from an inlet hole 25, compressed inside the compression chamber 22 and directed toward the center, where it is finally discharged from the compression chamber 22 by way of the outlet hole 43, discharge hole 44 and exhaust joint 45.
The sound of the exhaust gas that is discharged from the discharge hole 44 and exhaust joint 45 has a considerably high pitch, so normally a suitable silencer 50 is installed in the outlet of the discharge hole 44 or exhaust joint 45.
However, the silencer 50 protrudes outward in the axial or radial direction of the scroll fluid machine itself, so the dimensions of the scroll fluid machine are increased by that amount, which hinders handling and installation of the machine.